KVM: s390: Switch to new gmap

Switch KVM/s390 to use the new gmap code.

Remove includes to <gmap.h> and include "gmap.h" instead; fix all the
existing users of the old gmap functions to use the new ones instead.

Fix guest storage key access functions to work with the new gmap.

Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>

Author: Claudio Imbrenda

arch/s390/Kconfig

@@ -33,7 +33,7 @@ config GENERIC_LOCKBREAK
 	def_bool y if PREEMPTION
 
 config PGSTE
-	def_bool y if KVM
+	def_bool n
 
 config AUDIT_ARCH
 	def_bool y

arch/s390/include/asm/kvm_host.h

@@ -442,7 +442,7 @@ struct kvm_vcpu_arch {
 	bool acrs_loaded;
 	struct kvm_s390_pv_vcpu pv;
 	union diag318_info diag318_info;
-	void *mc; /* Placeholder */
+	struct kvm_s390_mmu_cache *mc;
 };
 
 struct kvm_vm_stat {
@@ -636,6 +636,8 @@ struct kvm_s390_pv {
 	struct mutex import_lock;
 };
 
+struct kvm_s390_mmu_cache;
+
 struct kvm_arch {
 	struct esca_block *sca;
 	debug_info_t *dbf;
@@ -675,6 +677,7 @@ struct kvm_arch {
 	struct kvm_s390_pv pv;
 	struct list_head kzdev_list;
 	spinlock_t kzdev_list_lock;
+	struct kvm_s390_mmu_cache *mc;
 };
 
 #define KVM_HVA_ERR_BAD		(-1UL)

arch/s390/include/asm/mmu_context.h

@@ -30,11 +30,7 @@ static inline int init_new_context(struct task_struct *tsk,
 	mm->context.gmap_asce = 0;
 	mm->context.flush_mm = 0;
 #if IS_ENABLED(CONFIG_KVM)
-	mm->context.has_pgste = 0;
-	mm->context.uses_skeys = 0;
-	mm->context.uses_cmm = 0;
 	mm->context.allow_cow_sharing = 1;
-	mm->context.allow_gmap_hpage_1m = 0;
 #endif
 	switch (mm->context.asce_limit) {
 	default:

arch/s390/include/asm/tlb.h

@@ -36,7 +36,6 @@ static inline bool __tlb_remove_folio_pages(struct mmu_gather *tlb,
 
 #include <asm/tlbflush.h>
 #include <asm-generic/tlb.h>
-#include <asm/gmap.h>
 
 /*
  * Release the page cache reference for a pte removed by
@@ -85,8 +84,6 @@ static inline void pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte,
 	tlb->mm->context.flush_mm = 1;
 	tlb->freed_tables = 1;
 	tlb->cleared_pmds = 1;
-	if (mm_has_pgste(tlb->mm))
-		gmap_unlink(tlb->mm, (unsigned long *)pte, address);
 	tlb_remove_ptdesc(tlb, virt_to_ptdesc(pte));
 }
 

arch/s390/include/asm/uaccess.h

@@ -471,65 +471,15 @@ do {									\
 #define arch_get_kernel_nofault __mvc_kernel_nofault
 #define arch_put_kernel_nofault __mvc_kernel_nofault
 
-void __cmpxchg_user_key_called_with_bad_pointer(void);
-
-int __cmpxchg_user_key1(unsigned long address, unsigned char *uval,
-			unsigned char old, unsigned char new, unsigned long key);
-int __cmpxchg_user_key2(unsigned long address, unsigned short *uval,
-			unsigned short old, unsigned short new, unsigned long key);
-int __cmpxchg_user_key4(unsigned long address, unsigned int *uval,
-			unsigned int old, unsigned int new, unsigned long key);
-int __cmpxchg_user_key8(unsigned long address, unsigned long *uval,
-			unsigned long old, unsigned long new, unsigned long key);
-int __cmpxchg_user_key16(unsigned long address, __uint128_t *uval,
-			 __uint128_t old, __uint128_t new, unsigned long key);
-
-static __always_inline int _cmpxchg_user_key(unsigned long address, void *uval,
-					     __uint128_t old, __uint128_t new,
-					     unsigned long key, int size)
-{
-	switch (size) {
-	case 1:  return __cmpxchg_user_key1(address, uval, old, new, key);
-	case 2:  return __cmpxchg_user_key2(address, uval, old, new, key);
-	case 4:  return __cmpxchg_user_key4(address, uval, old, new, key);
-	case 8:  return __cmpxchg_user_key8(address, uval, old, new, key);
-	case 16: return __cmpxchg_user_key16(address, uval, old, new, key);
-	default: __cmpxchg_user_key_called_with_bad_pointer();
-	}
-	return 0;
-}
-
-/**
- * cmpxchg_user_key() - cmpxchg with user space target, honoring storage keys
- * @ptr: User space address of value to compare to @old and exchange with
- *	 @new. Must be aligned to sizeof(*@ptr).
- * @uval: Address where the old value of *@ptr is written to.
- * @old: Old value. Compared to the content pointed to by @ptr in order to
- *	 determine if the exchange occurs. The old value read from *@ptr is
- *	 written to *@uval.
- * @new: New value to place at *@ptr.
- * @key: Access key to use for checking storage key protection.
- *
- * Perform a cmpxchg on a user space target, honoring storage key protection.
- * @key alone determines how key checking is performed, neither
- * storage-protection-override nor fetch-protection-override apply.
- * The caller must compare *@uval and @old to determine if values have been
- * exchanged. In case of an exception *@uval is set to zero.
- *
- * Return:     0: cmpxchg executed
- *	       -EFAULT: an exception happened when trying to access *@ptr
- *	       -EAGAIN: maxed out number of retries (byte and short only)
- */
-#define cmpxchg_user_key(ptr, uval, old, new, key)			\
-({									\
-	__typeof__(ptr) __ptr = (ptr);					\
-	__typeof__(uval) __uval = (uval);				\
-									\
-	BUILD_BUG_ON(sizeof(*(__ptr)) != sizeof(*(__uval)));		\
-	might_fault();							\
-	__chk_user_ptr(__ptr);						\
-	_cmpxchg_user_key((unsigned long)(__ptr), (void *)(__uval),	\
-			  (old), (new), (key), sizeof(*(__ptr)));	\
-})
+int __cmpxchg_key1(void *address, unsigned char *uval, unsigned char old,
+		   unsigned char new, unsigned long key);
+int __cmpxchg_key2(void *address, unsigned short *uval, unsigned short old,
+		   unsigned short new, unsigned long key);
+int __cmpxchg_key4(void *address, unsigned int *uval, unsigned int old,
+		   unsigned int new, unsigned long key);
+int __cmpxchg_key8(void *address, unsigned long *uval, unsigned long old,
+		   unsigned long new, unsigned long key);
+int __cmpxchg_key16(void *address, __uint128_t *uval, __uint128_t old,
+		    __uint128_t new, unsigned long key);
 
 #endif /* __S390_UACCESS_H */

arch/s390/include/asm/uv.h

@@ -631,7 +631,6 @@ int uv_pin_shared(unsigned long paddr);
 int uv_destroy_folio(struct folio *folio);
 int uv_destroy_pte(pte_t pte);
 int uv_convert_from_secure_pte(pte_t pte);
-int make_hva_secure(struct mm_struct *mm, unsigned long hva, struct uv_cb_header *uvcb);
 int s390_wiggle_split_folio(struct mm_struct *mm, struct folio *folio);
 int __make_folio_secure(struct folio *folio, struct uv_cb_header *uvcb);
 int uv_convert_from_secure(unsigned long paddr);

arch/s390/kernel/uv.c

@@ -209,39 +209,6 @@ int uv_convert_from_secure_pte(pte_t pte)
 	return uv_convert_from_secure_folio(pfn_folio(pte_pfn(pte)));
 }
 
-/**
- * should_export_before_import - Determine whether an export is needed
- * before an import-like operation
- * @uvcb: the Ultravisor control block of the UVC to be performed
- * @mm: the mm of the process
- *
- * Returns whether an export is needed before every import-like operation.
- * This is needed for shared pages, which don't trigger a secure storage
- * exception when accessed from a different guest.
- *
- * Although considered as one, the Unpin Page UVC is not an actual import,
- * so it is not affected.
- *
- * No export is needed also when there is only one protected VM, because the
- * page cannot belong to the wrong VM in that case (there is no "other VM"
- * it can belong to).
- *
- * Return: true if an export is needed before every import, otherwise false.
- */
-static bool should_export_before_import(struct uv_cb_header *uvcb, struct mm_struct *mm)
-{
-	/*
-	 * The misc feature indicates, among other things, that importing a
-	 * shared page from a different protected VM will automatically also
-	 * transfer its ownership.
-	 */
-	if (uv_has_feature(BIT_UV_FEAT_MISC))
-		return false;
-	if (uvcb->cmd == UVC_CMD_UNPIN_PAGE_SHARED)
-		return false;
-	return atomic_read(&mm->context.protected_count) > 1;
-}
-
 /*
  * Calculate the expected ref_count for a folio that would otherwise have no
  * further pins. This was cribbed from similar functions in other places in
@@ -313,20 +280,6 @@ int __make_folio_secure(struct folio *folio, struct uv_cb_header *uvcb)
 }
 EXPORT_SYMBOL(__make_folio_secure);
 
-static int make_folio_secure(struct mm_struct *mm, struct folio *folio, struct uv_cb_header *uvcb)
-{
-	int rc;
-
-	if (!folio_trylock(folio))
-		return -EAGAIN;
-	if (should_export_before_import(uvcb, mm))
-		uv_convert_from_secure(folio_to_phys(folio));
-	rc = __make_folio_secure(folio, uvcb);
-	folio_unlock(folio);
-
-	return rc;
-}
-
 /**
  * s390_wiggle_split_folio() - try to drain extra references to a folio and
  *			       split the folio if it is large.
@@ -414,56 +367,6 @@ int s390_wiggle_split_folio(struct mm_struct *mm, struct folio *folio)
 }
 EXPORT_SYMBOL_GPL(s390_wiggle_split_folio);
 
-int make_hva_secure(struct mm_struct *mm, unsigned long hva, struct uv_cb_header *uvcb)
-{
-	struct vm_area_struct *vma;
-	struct folio_walk fw;
-	struct folio *folio;
-	int rc;
-
-	mmap_read_lock(mm);
-	vma = vma_lookup(mm, hva);
-	if (!vma) {
-		mmap_read_unlock(mm);
-		return -EFAULT;
-	}
-	folio = folio_walk_start(&fw, vma, hva, 0);
-	if (!folio) {
-		mmap_read_unlock(mm);
-		return -ENXIO;
-	}
-
-	folio_get(folio);
-	/*
-	 * Secure pages cannot be huge and userspace should not combine both.
-	 * In case userspace does it anyway this will result in an -EFAULT for
-	 * the unpack. The guest is thus never reaching secure mode.
-	 * If userspace plays dirty tricks and decides to map huge pages at a
-	 * later point in time, it will receive a segmentation fault or
-	 * KVM_RUN will return -EFAULT.
-	 */
-	if (folio_test_hugetlb(folio))
-		rc = -EFAULT;
-	else if (folio_test_large(folio))
-		rc = -E2BIG;
-	else if (!pte_write(fw.pte) || (pte_val(fw.pte) & _PAGE_INVALID))
-		rc = -ENXIO;
-	else
-		rc = make_folio_secure(mm, folio, uvcb);
-	folio_walk_end(&fw, vma);
-	mmap_read_unlock(mm);
-
-	if (rc == -E2BIG || rc == -EBUSY) {
-		rc = s390_wiggle_split_folio(mm, folio);
-		if (!rc)
-			rc = -EAGAIN;
-	}
-	folio_put(folio);
-
-	return rc;
-}
-EXPORT_SYMBOL_GPL(make_hva_secure);
-
 /*
  * To be called with the folio locked or with an extra reference! This will
  * prevent kvm_s390_pv_make_secure() from touching the folio concurrently.
@@ -474,21 +377,18 @@ int arch_make_folio_accessible(struct folio *folio)
 {
 	int rc = 0;
 
-	/* Large folios cannot be secure */
-	if (unlikely(folio_test_large(folio)))
-		return 0;
-
 	/*
-	 * PG_arch_1 is used in 2 places:
-	 * 1. for storage keys of hugetlb folios and KVM
-	 * 2. As an indication that this small folio might be secure. This can
-	 *    overindicate, e.g. we set the bit before calling
-	 *    convert_to_secure.
-	 * As secure pages are never large folios, both variants can co-exists.
+	 * PG_arch_1 is used as an indication that this small folio might be
+	 * secure. This can overindicate, e.g. we set the bit before calling
+	 * convert_to_secure.
 	 */
 	if (!test_bit(PG_arch_1, &folio->flags.f))
 		return 0;
 
+	/* Large folios cannot be secure. */
+	if (WARN_ON_ONCE(folio_test_large(folio)))
+		return -EFAULT;
+
 	rc = uv_pin_shared(folio_to_phys(folio));
 	if (!rc) {
 		clear_bit(PG_arch_1, &folio->flags.f);

arch/s390/kvm/Makefile

@@ -8,7 +8,7 @@ include $(srctree)/virt/kvm/Makefile.kvm
 ccflags-y := -Ivirt/kvm -Iarch/s390/kvm
 
 kvm-y += kvm-s390.o intercept.o interrupt.o priv.o sigp.o
-kvm-y += diag.o gaccess.o guestdbg.o vsie.o pv.o gmap-vsie.o
+kvm-y += diag.o gaccess.o guestdbg.o vsie.o pv.o
 kvm-y += dat.o gmap.o faultin.o
 
 kvm-$(CONFIG_VFIO_PCI_ZDEV_KVM) += pci.o

arch/s390/kvm/diag.c

@@ -10,13 +10,13 @@
 
 #include <linux/kvm.h>
 #include <linux/kvm_host.h>
-#include <asm/gmap.h>
 #include <asm/gmap_helpers.h>
 #include <asm/virtio-ccw.h>
 #include "kvm-s390.h"
 #include "trace.h"
 #include "trace-s390.h"
 #include "gaccess.h"
+#include "gmap.h"
 
 static void do_discard_gfn_range(struct kvm_vcpu *vcpu, gfn_t gfn_start, gfn_t gfn_end)
 {